Galacticraft: a cross between Kerbal Space Program and Minecraft

If
you ever wanted your face on a flag, a flag that you can plunge into
the soil of an alien world, then look no further than Galacticraft. This
Minecraft mod gives you the chance to indulge in your own, home-grown
space program, building bespoke rockets in your backyard and exploring
the great beyond.

Waiting
for you out in space are other planets with their own terrain
generation routines, with their own resources and even with their own
gravity. Galacticraft is an ambitious mod that’s still at a very early
stage, but it’s worth playing.

Building
a rocket ship has never been easier. Galacticraft provides a new
workbench-style interface that lets you put together components like
engines, fins and a nose cone, many of which are built from the three
new ores the mod introduces: titanium, copper and aluminium. Climbing
into your new ship, you’ll be presented with a list of other planets
that you can visit, but before you set foot on another world you’ll want
to make sure you’ve crafted a few oxygen tanks and have a moon buggy
ready. Oh, and don’t forget that airless surface of other planets will
be deadly silent. Whatever you find up there won’t make any sort of
noise.

Galacticraft
is still a very young mod and needs a great deal of development, but it
looks extremely promising. Right now it has a pretty unremarkable web
page on its creator’s blog
and it’s not yet available for download, but, that hasn’t stopped
YouTuber DaveChaos from requesting an early build, exploring the final
frontier and discovering that there may indeed be life on Mars. Here’s
what he found:

This is definitely a mod to keep an eye on. If you want to give it a go now, it may be worth politely asking creator Micdoodle8 if he'll let you have a go with an early version. (There's no harm in trying, right?)